JPH08251954A - Ultrasonic oscillator - Google Patents

Abstract

PURPOSE: To obtain a highly reliable rod-like ultrasonic oscillator by preventing insufficient conduction due to chipping of a flexible printed board. CONSTITUTION: The rod-like ultrasonic oscillator 1 comprises a multilayer piezoelectric element 5 and a flexible printed board 6 for feeding power thereto clamped by upper and lower oscillators 2, 3. A cutting prevention means for controlling the strength distribution of the flexible printed board 6 with respect to the bending stress is provided in the vicinity of the conducting part of the flexible printed board 6 serving as an electric contact between the rod-like ultrasonic oscillator 1 and an external connector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rod-shaped ultrasonic oscillator suitable for use in, for example, a rod-shaped ultrasonic motor, and more particularly to an ultrasonic oscillator having a flexible printed board.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view of a rod-shaped ultrasonic transducer 1 showing a conventional technique. The rod-shaped ultrasonic vibrator 1 has a metallic upper vibrating body 2 and a lower vibrating body 3, a laminated piezoelectric element 5 and a flexible printed circuit board 6 which are arranged so as to be sandwiched therebetween, and are fastened with fastening bolts 4 to form an integrated structure. It is composed of Shape of vibrator 1, laminated piezoelectric element 5
The configuration, the operation of driving the rod-shaped ultrasonic transducer 1 for excitation, and the like are not related to the present invention, and a description thereof will be omitted.

FIG. 6 shows a structure of a flexible printed board 6 used in the conventional rod-shaped ultrasonic vibrator shown in FIG. The flexible printed circuit board 6 is a rod-shaped ultrasonic transducer 1
The lower vibrating body 3 and the laminated piezoelectric element 5, which are included in the above, are clamped and clamped between the lower vibrating body 3 and the laminated piezoelectric element 5. −
It is composed of a conducting part 6-b for conducting with c, a substrate electrode 7, and a cover coat part 8 for electrically insulating.

[0004]

However, in the structure of the above-mentioned conventional flexible printed circuit board,
When assembling the rod-shaped ultrasonic vibrator, cutting occurs at the protruding portion of the flexible printed circuit board from the vibrator during driving,
Continuity failure occurred. This occurs because a bending force is applied to the flexible printed circuit board in an out-of-plane direction when the rod-shaped ultrasonic transducer is assembled and driven.

Originally, the width of the flexible printed circuit board should be widened, but in consideration of the environment in which the rod-shaped ultrasonic transducer is used, there is a problem that the flexible printed circuit board interferes with other structures. Further, the rod-shaped ultrasonic vibrator is a device for converting electric energy into mechanical vibration energy to obtain a mechanical output, and an increase in the loss of vibration energy is directly related to the performance of the rod-shaped ultrasonic vibrator. The flexible printed circuit board uses a relatively soft material such as polyimide resin for the base, and an increase in the mass of the flexible printed circuit board causes an increase in the energy loss of the rod-shaped ultrasonic vibrator, resulting in a decrease in the performance of the vibrator. So not desirable.

An object of the present invention is to provide a highly reliable rod-shaped ultrasonic vibrator which prevents defective conduction due to cutting of the flexible printed circuit board.

[0007]

According to a first aspect of the present invention, there is provided a piezoelectric element and a flexible substrate for feeding power to the piezoelectric element. In an ultrasonic vibrator sandwiched and fixed between vibrators, the flexible substrate includes a sandwiching part sandwiched and fixed between the oscillators, a connecting part electrically connected to the outside, and the sandwiching part and the connecting part. The ultrasonic transducer is characterized in that a cutting prevention means is provided in the vicinity of the sandwiching portion of the conducting portion so as to control the strength distribution with respect to the bending stress of the flexible substrate.

According to this structure, it is possible to prevent defective conduction due to cutting of the flexible printed circuit board, and to provide a highly reliable rod-shaped ultrasonic transducer or the like.

As the cutting preventing means having the above-mentioned structure, as described in claim 2, in claim 1, a notch portion for reducing the second moment of area is provided in the vicinity of the sandwiching portion of the conducting portion. It is characterized by being configured flexibly.

According to this structure, it is possible to improve the bending durability and the cutting resistance of the flexible printed circuit board and prevent the conduction failure due to the cutting loss.

As another cutting prevention means having the above-mentioned structure, as in claim 3, in claim 2, an end of a cover coat for insulatingly covering the conducting portion at the same position as the cutout portion. The parts may be positioned and configured.

According to this structure, stress is likely to be concentrated in the cutout portion of the flexible printed board, and bending deformation can be applied to the cutout portion with a sufficient curvature.

As another cutting prevention means having the above-mentioned structure, as described in claim 4, in claim 1, the electrode of the flexible printed circuit board is annealed.

According to this structure, it is possible to prevent the electrodes of the flexible printed circuit board from being cut off by annealing the copper foil or the like forming the electrodes of the flexible printed circuit board.

As another cutting prevention means having the above-mentioned structure, as described in claim 5, in claim 1, by having a bent portion in the plane of the flexible substrate in the vicinity of the holding portion of the conducting portion. can get.

According to this structure, the deformation stress strain applied to the connecting portion can be dispersed only in the conducting portion.

As a cutting prevention means combining the above-mentioned respective structures, as described in claim 6, in claim 1, a notch portion for reducing the second moment of area in the vicinity of the sandwiching portion of the conducting portion, The flexible substrate has a bent portion in a plane, and an end portion of a cover coat for insulatingly coating the conductive portion is positioned at the same position as the cutout portion to improve the extension ratio of the electrode of the flexible substrate. As described above, the electrode is annealed.

According to this structure, it is possible to provide a highly reliable rod-shaped ultrasonic transducer or the like at low cost.

[0019]

【Example】

(First Embodiment) FIG. 1 is an exploded perspective view of a rod-shaped ultrasonic transducer 1 according to the first embodiment of the present invention. The configuration of the rod-shaped ultrasonic transducer 1 is the same as that of the conventional example, and the description is omitted.
FIG. 2 shows a planar shape of the flexible printed board 6 used in the first embodiment according to the present invention. The flexible printed circuit board 6 is sandwiched between the lower vibrating body 3 which constitutes the rod-shaped ultrasonic transducer 1 and the laminated piezoelectric element 5 and is clamped and clamped, and a connecting portion 6-a for connection with a connector for conduction (not shown). c, a conducting portion 6-b for conducting the holding portion 6-a and the connecting portion 6-c, an electrode 7, and a cover coat portion 8 for electrically insulating.

Since the vibrator 1 in this embodiment is electrically driven in two phases, each driving phase has an independent ground phase, and has a sensor phase that serves as a sensor, it is possible to electrically connect to the outside. The total number of connections is 5 phases. Since all the electrical connections are made by the flexible printed board 6, the flexible printed board 6 has five board electrodes 7
Is formed. The driving method of the vibrator 1 shown here, the configuration of the laminated piezoelectric element 5, and the like have no direct relation to the present invention, and therefore the description thereof is omitted.

The base of the flexible printed circuit board 6 is made of polyimide resin and has a thickness of about 25 μm.

The electrodes 7 of the flexible printed board 6 are formed of copper foil and have a thickness of about 35 μm. The exposed portion of the copper foil is solder-plated to prevent the copper foil from being oxidized. Conducting part 6 of flexible printed circuit board 6-
The cover coat portion 8 for insulation on b is formed of a polyimide resin and has a thickness of about 25 μm. The electrode 7 of the flexible printed circuit board 6 is formed by adhering it to the base material with an adhesive, and an epoxy adhesive is used, and the thickness is 15 μm on average.

The diameter of the rod-shaped ultrasonic transducer 1 is φ10 mm, and the diameter of the sandwiching portion 6-a of the flexible printed board 6 is also φ10 mm. The distance from the center of the holding portion 6-a to the end of the connecting portion 6-c is about 40 mm. Conducting part 6
The width of -c is about 3.25 mm. The widths of the electrodes 7 formed in the conducting portions 6-c are all about 0.25 mm and the pitch is about 0.5 mm.

Conducting portion 6 of flexible printed circuit board 6-
In b, a notch 6-d is formed at a position about 6.2 mm from the center of the holding part 6-a, that is, at a position 1.2 mm away from the side surface of the vibrator so as to face both side surfaces of the conducting part 6-b. It The width of the conducting portion 6-b at the position of the cutout portion is about 2.8 mm. In addition, the end portion 8 of the cover coat portion 8 on the conducting portion 6-b.
-A is formed so as to be at the same position as the cutout 6-d.

As described in the section of the problem to be solved, when the width and thickness of the connecting portion 6-c of the flexible printed circuit board 6 are increased, the loss of vibration energy due to the flexible printed circuit board 6 is increased, and the performance of the vibrator is increased. Will lead to a decrease in Further, considering the usage state of the rod-shaped ultrasonic transducer 1, the width of the conducting portion 6-b of the flexible printed circuit board 6 cannot be increased beyond the above value.

In the vibrator 1 of this embodiment, when the flexible printed circuit board 6 is subjected to a bending force in the out-of-plane direction, the second moment of area becomes small due to the notch 6-d provided in the conducting portion 6-b. Therefore, the strength against bending is lower than the other portions, and this portion is flexible and easy to bend. Further, the end portion 8-a of the cover coat portion 8 is formed so as to be aligned with the cutout portion 6-d, and stress is concentrated on the cutout portion 6-d due to the effect of the end portion 8-a. It has an easy structure. Therefore, the flexible printed circuit board is bent and deformed with a sufficient curvature as shown in FIG. 3, and as a result, the electrodes 7 of the flexible printed circuit board 6 are deformed.
It is possible to provide a highly reliable rod-shaped ultrasonic transducer 1 which is free from cutting.

In this embodiment, the laminated piezoelectric element 5 is adopted as the piezoelectric element, but the piezoelectric element is not limited to this and may be a piezoelectric element composed of one plate. Further, the shape of the vibrator 1, the vibrator 1 and the flexible printed board 6
The shape and dimensions of are not limited to those in this embodiment.

(Second Embodiment) Next, a second embodiment according to the present invention will be described. The shape of the flexible printed circuit board 6 in the second embodiment is the same as that of FIG. 1 shown in the first embodiment, and the explanation is omitted.

It was confirmed by observation that the disconnection of the electrode 7 of the flexible printed circuit board 6 that occurred in the conventional example was caused by the lack of ductility of the copper foil. Flexible printed circuit board 6
The copper foil used in the above is formed by rolling or electrolytic process, but it is not annealed in the process of forming the flexible printed circuit board 6. The draw ratio of this copper foil was about 4 percent.

Next, about 20 flexible printed circuit boards 6 are provided.
When it was annealed at 0 ° C. and the stretching ratio was also measured, it was improved to 10%. When this flexible printed board 6 was assembled to the rod-shaped ultrasonic vibrator 1 in the same manner as in Example 1, cutting was not generated in the electrodes 7 of the flexible printed board 6, and good results were obtained.

In the above structure, an epoxy-based adhesive is used to bond the electrode 7 of the flexible printed board 6 to the base, and the temperature at which the copper foil is annealed depends on the heat resistance of this adhesive. Depends on. When an adhesive-free substrate material that does not use an adhesive is used to bond the copper foil and the base as the material of the flexible printed board 6, the annealing temperature of the copper foil is up to 250 ° C. As a result, the stretchability of the copper foil is further increased, and the flexible printed circuit board 6 having excellent cut resistance can be formed.

As described above, according to this embodiment, the problem of cutting the electrode 7 of the flexible printed board 6 is solved, and the highly reliable rod-shaped ultrasonic vibrator 1 is provided.

The effect of this embodiment is not limited to the shape of the flexible printed board 6. (Third Embodiment) FIG. 4 shows a flexible printed circuit board 6 according to a third embodiment of the present invention. The structure of the rod-shaped ultrasonic transducer 1 is the same as that of the first embodiment, and the description thereof is omitted here.

The flexible printed board 6 has a conducting portion 6-
In b, it is bent in the plane by about 90 ° at a position separated by about 10 mm from the central portion of the holding portion 6-a.

A deforming force on the flexible printed circuit board 6 is applied from the connecting portion 6-c. Further, the resistance to deformation or the strength of the flexible printed circuit board 6 is larger in the in-plane direction than in the out-plane direction. In the shape like the conventional example shown in FIG. 6, the deforming force applied from the connecting portion 6-c causes direct deformation in the vicinity of the holding portion 6-a of the conducting portion 6-b.

As in the present embodiment, the flexible printed circuit board 6 is bent in the horizontal plane at the conducting portion 6-b, so that the strain due to the deformation force applied to the connecting portion 6-c causes the flexible printed circuit board 6 to conduct. It is possible to prevent disconnection of the electrodes 7 of the flexible printed board 6 by preventing the stress from being concentrated on a part of the flexible printed circuit board 6 by being dispersed in the portion 6-b. The first to third embodiments can naturally be combined.

[0037]

According to the first aspect of the present invention, it is possible to provide a highly reliable, for example, rod-shaped ultrasonic transducer or the like, which prevents conduction failure due to cutting of the flexible printed circuit board.

According to the second aspect of the present invention, the flexible printed circuit board is improved in bending durability and cut resistance,
It is possible to prevent defective conduction due to cutting.

According to the third aspect of the present invention, stress is likely to be concentrated in the cutout portion of the flexible printed board, and bending deformation can be applied to the cutout portion with a sufficient curvature.

According to the fourth aspect of the invention, the electrodes of the flexible printed circuit board can be prevented from being cut by annealing the copper foil or the like forming the electrodes of the flexible printed circuit board.

According to the fifth aspect of the invention, the deformation stress strain applied to the connecting portion can be dispersed only in the conducting portion.

According to the sixth aspect of the invention, it is possible to provide a highly reliable, for example, rod-shaped ultrasonic transducer at a low cost.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a rod-shaped ultrasonic transducer according to a first embodiment.

FIG. 2 is a plan view of a flexible printed circuit board used in the first embodiment.

FIG. 3 is a side view showing a state in which the flexible printed circuit board is bent in the first embodiment.

FIG. 4 is a plan view of a flexible printed circuit board used in the third embodiment.

FIG. 5 is an overall perspective view of a conventional rod-shaped ultrasonic transducer.

FIG. 6 is a plan view of a conventional flexible printed circuit board.

FIG. 7 is a side view showing a state in which a flexible printed circuit board is bent in a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rod-shaped ultrasonic vibrator 2 ... Upper vibrator 3 ... Lower vibrator 4 ... Fastening bolt 5 ... Laminated piezoelectric element 6 ... Flexible printed circuit board 7 ... Electrode 8 ... Cover coat part

Claims (6)

[Claims] 1. An ultrasonic transducer comprising a piezoelectric element and a flexible substrate for feeding power to the piezoelectric element sandwiched and fixed between two vibrating bodies, wherein the flexible substrate is sandwiched and fixed between the vibrating bodies. A sandwiching portion, a connecting portion electrically connected to the outside, and a conducting portion that conducts electricity between the sandwiching portion and the connecting portion are provided, and a strength distribution against bending stress of the flexible substrate is provided near the sandwiching portion of the conducting portion. An ultrasonic transducer, which is provided with cutting prevention means for controlling. 2. The cut preventing means according to claim 1, wherein the cut preventing means is configured to be flexible by providing a cutout portion for reducing a moment of inertia of area in the vicinity of the sandwiching portion of the conducting portion. Ultrasonic transducer. 3. The ultrasonic transducer according to claim 2, wherein an end portion of a cover coat for insulatingly coating the conducting portion is positioned at the same position as the cutout portion. 4. The ultrasonic transducer according to claim 1, wherein the electrode of the flexible substrate is annealed as a cutting prevention means. 5. The ultrasonic transducer according to claim 1, wherein the cutting prevention means has a bent portion in the plane of the flexible substrate near the sandwiching portion of the conducting portion. 6. The cutting prevention means according to claim 1, wherein the cutting prevention means has a cutout portion for reducing a moment of inertia of area in the vicinity of the holding portion of the conducting portion, and a bending portion in a plane of the flexible substrate. An end portion of a cover coat for insulatingly coating the conductive portion is positioned at the same position as the cutout portion, and the electrode of the flexible substrate is annealed so as to improve the extension ratio of the electrode. Ultrasonic transducer.